The pilots interviewed reported that the Mallard was a cumbersome and difficult vessel to handle. While the pilot of the Mallard had considerable experience of Great Lakes vessels, he had relatively limited seaway experience of the handling characteristics of conventional ocean-going vessels. Although the pilots who had piloted the Mallard attributed the difficulties experienced in handling the vessel to her beam to length ratio, the ratio is usual for sea-going vessels of similar size. Other factors, such as rudder type and size, block co-efficient and under keel clearance also affect steering. On an even keel, the Mallard, like many full-bodied ships, does not have the same handling characteristics as vessels designed for Seaway service which are proportionally longer. Handling can be significantly improved by trimming the vessel by the stern but because the vessel was at near- maximum Seaway draught and trimmed by the head, this was not an option available to the master. The hard-over position of the rudders of sea-going vessels is normally 35 degrees and of Great Lakes vessels is about 45 degrees.[3] While not all of this increased steering potential is proportionally useful, this difference, combined with a slower response in manoeuverability may further explain some of the pilot's difficulties. The speed of approach of the Mallard to the approach wall ( 3kts) was below the minimum (3.5 kts) at which steerage way could be theoretically maintained. Even when a vessel has directional stability it is difficult to steer if she is allowed to come alongside the wall bodily. The angle of approach to the lock wall, must be maintained to avoid the loss of control until judgement by the pilot or master dictates that the angle needs to be reduced to meet another vessel safely in the narrow canal section. Due to transverse thrust, a vessel with a right-handed propeller turning ahead has a natural tendency to cant her stern to starboard. When the Mallard came bodily alongside the wall, the water displaced by the propeller between her stern and the wall aggravated this tendency and drew the stern further towards the wall. As the vessel's speed (engine revolutions) was increased so did the bank suction effect - to the point where hard-to-starboard rudder was applied. The stern of the Mallard was observed to remain close to the lock approach wall and the helm applied had little or no effect on the vessel's heading or in preventing her bow from turning out into the channel towards the CanadianEnterprise. At this point, the pilot's options to regain control of the vessel were limited. Despite the stern's proximity to the approach wall, the engine was ordered full astern. This manoeuvre would normally cause the vessel's stern to cant to port and start to reduce headway, however the vessel's stern was already being drawn towards the approach wall and there was insufficient time for the propeller to 'bite' and counter the bank-suction. Because of the cavitation at the stern and the bank suction effect, this manoeuvre was unsuccessful in avoiding collision but it may have reduced the collision's severity. The angle of collision would appear to have been nearer to 20 degrees rather than the 30 degrees estimated, given the length and positioning of the vessels in the narrow channel. The area of the collision was in close proximity to a submarine pipeline. Anchoring in this part of the Seaway, except in emergencies, is prohibited and the pilot was reluctant to employ the vessel's anchor because of this. In addition, the Mallard had a small under-keel clearance and there existed the very real danger of holing the ship were she to run over the anchor. This danger was minimized because the vessel was nearly stopped when the starboard anchor was let go on a short scope of chain. In the event, neither the pipeline nor the ship was damaged. Based upon the information supplied by the pilot and the medical opinion of two physicians, it appears unlikely that his use of a topical eye lubricant had an effect on his vision or depth perception at the time of the occurrence. The residual side- effects of the pilot's completed course of prescription medication, however, are unknown. The vessel's weather observations were taken when she was on the open water of Lake Ontario before the vessel entered the sheltered area of Port Weller piers. The wind strength recorded on the lake was considerably higher than that recorded by the automatic weather recording station at Port Weller. Because the wind speeds and visibility recorded by the station were closer in location and in time to that of the occurrence, these readings have been accepted as being more accurate. The wind speeds and weather recorded by the automatic weather station make it unlikely that weather was a factor in the occurrence.Analysis The pilots interviewed reported that the Mallard was a cumbersome and difficult vessel to handle. While the pilot of the Mallard had considerable experience of Great Lakes vessels, he had relatively limited seaway experience of the handling characteristics of conventional ocean-going vessels. Although the pilots who had piloted the Mallard attributed the difficulties experienced in handling the vessel to her beam to length ratio, the ratio is usual for sea-going vessels of similar size. Other factors, such as rudder type and size, block co-efficient and under keel clearance also affect steering. On an even keel, the Mallard, like many full-bodied ships, does not have the same handling characteristics as vessels designed for Seaway service which are proportionally longer. Handling can be significantly improved by trimming the vessel by the stern but because the vessel was at near- maximum Seaway draught and trimmed by the head, this was not an option available to the master. The hard-over position of the rudders of sea-going vessels is normally 35 degrees and of Great Lakes vessels is about 45 degrees.[3] While not all of this increased steering potential is proportionally useful, this difference, combined with a slower response in manoeuverability may further explain some of the pilot's difficulties. The speed of approach of the Mallard to the approach wall ( 3kts) was below the minimum (3.5 kts) at which steerage way could be theoretically maintained. Even when a vessel has directional stability it is difficult to steer if she is allowed to come alongside the wall bodily. The angle of approach to the lock wall, must be maintained to avoid the loss of control until judgement by the pilot or master dictates that the angle needs to be reduced to meet another vessel safely in the narrow canal section. Due to transverse thrust, a vessel with a right-handed propeller turning ahead has a natural tendency to cant her stern to starboard. When the Mallard came bodily alongside the wall, the water displaced by the propeller between her stern and the wall aggravated this tendency and drew the stern further towards the wall. As the vessel's speed (engine revolutions) was increased so did the bank suction effect - to the point where hard-to-starboard rudder was applied. The stern of the Mallard was observed to remain close to the lock approach wall and the helm applied had little or no effect on the vessel's heading or in preventing her bow from turning out into the channel towards the CanadianEnterprise. At this point, the pilot's options to regain control of the vessel were limited. Despite the stern's proximity to the approach wall, the engine was ordered full astern. This manoeuvre would normally cause the vessel's stern to cant to port and start to reduce headway, however the vessel's stern was already being drawn towards the approach wall and there was insufficient time for the propeller to 'bite' and counter the bank-suction. Because of the cavitation at the stern and the bank suction effect, this manoeuvre was unsuccessful in avoiding collision but it may have reduced the collision's severity. The angle of collision would appear to have been nearer to 20 degrees rather than the 30 degrees estimated, given the length and positioning of the vessels in the narrow channel. The area of the collision was in close proximity to a submarine pipeline. Anchoring in this part of the Seaway, except in emergencies, is prohibited and the pilot was reluctant to employ the vessel's anchor because of this. In addition, the Mallard had a small under-keel clearance and there existed the very real danger of holing the ship were she to run over the anchor. This danger was minimized because the vessel was nearly stopped when the starboard anchor was let go on a short scope of chain. In the event, neither the pipeline nor the ship was damaged. Based upon the information supplied by the pilot and the medical opinion of two physicians, it appears unlikely that his use of a topical eye lubricant had an effect on his vision or depth perception at the time of the occurrence. The residual side- effects of the pilot's completed course of prescription medication, however, are unknown. The vessel's weather observations were taken when she was on the open water of Lake Ontario before the vessel entered the sheltered area of Port Weller piers. The wind strength recorded on the lake was considerably higher than that recorded by the automatic weather recording station at Port Weller. Because the wind speeds and visibility recorded by the station were closer in location and in time to that of the occurrence, these readings have been accepted as being more accurate. The wind speeds and weather recorded by the automatic weather station make it unlikely that weather was a factor in the occurrence. The Mallard was reported to be a cumbersome and difficult vessel to handle. The manoeuverability of the Mallard was affected by the fact that the vessel was not trimmed by the stern at near-maximum Seaway draft, and relatively slower rudder response to helm instructions . The beam to length ratio of the Mallard was not unusual for a vessel of her size and class. The ratio was, however, greater than the Great Lakes vessels of which the pilot had considerable shiphandling experience. The Mallard approached the tie-up wall at a speed marginally below the minimum required to maintain steerage way. Directional control of the Mallard was lost after her bow landed on the approach wall and the vessel came bodily alongside. The vessel's stern was drawn against the tie up wall by bank suction effect as the engine rpm were increased and her bow swung towards the CanadianEnterprise. Due to the bank suction effect, the increases in speed ordered by the pilot to attempt to regain control of the vessel were unsuccessful. The order of full astern was given too late to avoid collision with the Canadian Enterprise but may have lessened the severity of the impact. The deployment of the vessel's starboard anchor near the centre of the channel probably prevented the Mallard from pushing the stern of the CanadianEnterprise aground. According to the pilot and to the opinion of two medical practitioners, the pilot's use of a topical eye lubricant about ten minutes before the occurrence was not likely to have affected his vision or depth perception. The residual side- effects, if any, of the pilot's completed course of prescription medication are unknown. Although in restricted waters, the CanadianEnterprise did all she could to avert a collision by going full astern the moment she was aware that the Mallard had serious difficulty controlling her movements. The action taken by the master and officers of the CanadianEnterprise to warn the ship's crew of the impending collision via the vessel's public address system probably prevented injury to personnel, especially those in the port side accommodation spaces. Passing entries are common in the Welland Canal. Apart from minor occurrences where ships have brushed against each other, no similar occurrence has taken place in this area of the canal.Findings The Mallard was reported to be a cumbersome and difficult vessel to handle. The manoeuverability of the Mallard was affected by the fact that the vessel was not trimmed by the stern at near-maximum Seaway draft, and relatively slower rudder response to helm instructions . The beam to length ratio of the Mallard was not unusual for a vessel of her size and class. The ratio was, however, greater than the Great Lakes vessels of which the pilot had considerable shiphandling experience. The Mallard approached the tie-up wall at a speed marginally below the minimum required to maintain steerage way. Directional control of the Mallard was lost after her bow landed on the approach wall and the vessel came bodily alongside. The vessel's stern was drawn against the tie up wall by bank suction effect as the engine rpm were increased and her bow swung towards the CanadianEnterprise. Due to the bank suction effect, the increases in speed ordered by the pilot to attempt to regain control of the vessel were unsuccessful. The order of full astern was given too late to avoid collision with the Canadian Enterprise but may have lessened the severity of the impact. The deployment of the vessel's starboard anchor near the centre of the channel probably prevented the Mallard from pushing the stern of the CanadianEnterprise aground. According to the pilot and to the opinion of two medical practitioners, the pilot's use of a topical eye lubricant about ten minutes before the occurrence was not likely to have affected his vision or depth perception. The residual side- effects, if any, of the pilot's completed course of prescription medication are unknown. Although in restricted waters, the CanadianEnterprise did all she could to avert a collision by going full astern the moment she was aware that the Mallard had serious difficulty controlling her movements. The action taken by the master and officers of the CanadianEnterprise to warn the ship's crew of the impending collision via the vessel's public address system probably prevented injury to personnel, especially those in the port side accommodation spaces. Passing entries are common in the Welland Canal. Apart from minor occurrences where ships have brushed against each other, no similar occurrence has taken place in this area of the canal. The Mallard collided with the CanadianEnterprise as a result of a loss of control over the vessel's steering and the angle of approach to the lock tie-up wall which caused the bow of the Mallard to swing across the canal. Contributing to the loss of control were the trim of the vessel and the effect of bank suction on the vessel's stern when the vessel came bodily alongside the tie-up wall. The emergency actions taken by both vessels probably lessened the severity of the collision and avoided injury to personnel.Causes and Contributing Factors The Mallard collided with the CanadianEnterprise as a result of a loss of control over the vessel's steering and the angle of approach to the lock tie-up wall which caused the bow of the Mallard to swing across the canal. Contributing to the loss of control were the trim of the vessel and the effect of bank suction on the vessel's stern when the vessel came bodily alongside the tie-up wall. The emergency actions taken by both vessels probably lessened the severity of the collision and avoided injury to personnel.